In this study, to investigate the influence of support crystalline phase structure on the dispersion behaviors of the supported metal oxides, tetragonal rutile RuO2 supported on both tetragonal anatase a-TiO2 and tetragonal rutile r-TiO2 supports with different loadings have been prepared, characterized and probed by CO oxidation. It has been discovered that the monolayer dispersion capacity of RuO2 on r-TiO2 support is 0.84 mmol per 100 m(2) surface, which is much higher than 0.15 mmol per 100 m(2) surface on a-TiO2 support. Due to the close matching of the crystalline phase and lattice parameters between RuO2 and r-TiO2 , Ru-O-Ti interfacial bonds can be effectively formed, thus facilitating the RuO2 dispersion and resulting in a high monolayer dispersion capacity. On the contrary, the big difference of the crystalline phase and lattice parameters between RuO2 and a-TiO2 support impedes the formation of Ru-O-Ti interfacial bonds and Ru0 2 dispersion, resulting in a low monolayer dispersion capacity. As a result, RuO2 has a much stronger interaction with r-TiO2 than with a-TiO2 support, which can generate more abundant mobile oxygen sites. Therefore, in comparison with RuO2/a-TiO2 , the intrinsic activity of RuO2/r-TiO2 for CO oxidation is remarkably enhanced. On the basis of the results, it is rational to propose that a like-disperses-like phenomenon is present in the supported metal oxide systems.